This disclosure relates generally to television receivers, and is particularly directed to mounting of cathode ray tubes in receiver cabinets.
A television receiver commonly consists of a cabinet made of wood, metal or a plastic having an open back for access to the components. The largest of these components is the cathode ray picture tube which has a substantially rectangular face panel with a rearwardly extending flange encircled by a tension band, and attached to a funnel portion and a neck portion oriented on the axis of the tube. The electronic section of the receiver is usually subdivided into parts placed at convenient locations beneath and at the sides of the cathode ray tube. The open back is normally covered by a panel that restricts access to the components.
The large face plate on which the broadcast television picture is reproduced, is viewed through a frontal escutcheon means with an opening for conformally receiving the cathode ray tube face panel. The face panel, which is normally oriented so as to be flush with the front of the cabinet, or slightly recessed therein, is supported and framed by the escutcheon, which is cast or otherwise formed from metal or plastic. The escutcheon also serves to cover the gap between the face plate and the cabinet front.
The awkward configuration, and the bulk and weight of the cathode ray picture tube makes it difficult to mount in the cabinet. And it is considered best that it be firmly mounted, yet without such a concentration of pressure at the mounting points that the brittle glass envelope is cracked or fractured. Also, it is preferable that the tube be firmly mounted so as ato be resistant to the shock which results from handling and shipping; such shock can result in tube breakage, or equally serious, the permanent displacement of the spring-mounted shadow mask in the color tube. To ameliorate the effects of rough handling of the receiver, resilient means for absorbing shock have been introduced into prior art tube-mounting means. An example is the mounting bracket disclosed by Goetz, Jr. in U.S. Pat. No. 3,651,257 wherein the bracket includes a pivotable portion coverable with a shock absorbent band for providing a soft engaging contact with the front screen of the picture tube. Another example is disclosed by Hirsch et al in U.S. Pat. No. 4,247,871, wherein a sealing gasket serves to resiliently mount the face plate section in conjunction with a color filter.
The problems of mounting cathode ray picture tubes are aggravated by the tolerance variations of manufactured tubes. As a practical matter, it is impossible to cast or mold the face plate-and flange sections to exact dimensions, as the glass will shrink unpredictably as it cools. The circumference of a nineteen-inch tube, for example, will vary by as much as .+-.78 mils, and the mounting means must be able to accommodate this range. Face panels of picture tubes of like diagonal dimension characterized by this exhibiting of relatively dissimilar circumferential dimensions, can be classified as under-, normal-, and over-sized panels.
Another problem is implicit in the sheer weight of the cathode ray tube, especially those of larger size (e.g., fifty-five pounds for the twenty-three-inch tube) making it mandatory that the mounting means be able to tolerate a force of at least the 30 g's commonly experienced during shipment.
Other prior art setting forth cathode ray tube mounting means includes the following:
St. George et al--U.S. Pat. No. 3,643,020 discloses a wire loop means for mounting a picture tube.
Stute--U.S. Pat. No. 3,712,958 discloses a picture tube escutcheon mounting member which, in addition to providing means for mounting the escutcheon, serves by its resiliency to cushion the picture tube from fortuitous shocks to the cabinet.